This invention is concerned with a yieldable gripper unit for a conveyor of the type in which gripper units ride on rails and are pulled by chains to form two endless tracks which are positioned in opposed facing relationship. The endless tracks converge to engage and support a sheet of material which is clamped and transported between them. In such a unit, one of the endless conveyor tracks is equipped with non-yielding gripper units and the other is equipped with yieldable gripper units. This invention is concerned with the yieldable gripper units. Prior yieldable gripper units have included a rigid metallic plate or supporting block having a resilient surface in the form of a channel shaped pad of rubber or other yieldable material adhesively fastened thereto on the outer face thereof. Each of these gripper units was mounted on a pair of studs each of which was surrounded by a coil spring to provide yielding movement of the resilient surface covered supporting block. A gripper unit of this type is shown in U.S. Pat. No. 2,754,956, issued July 17, 1956.
A later improvement replaced the spring mounted supporting block with a molded rubber compression pad. However, it was difficult to control the range of yield of the molded rubber compression pad.
An object of this invention is a yieldable gripper unit in which the yieldability or resilience of the unit can be readily controlled.
Another object of this invention is a yieldable gripper unit which can be modified to handle different thicknesses of material.
Another object of this invention is a yieldable gripper unit in which the range of yieldability or resilience is greatly increased.
Another object of this invention is a flexible gripper unit that can be readily attached to and removed from a conveyor unit.
Other objects may be found in the following specification, claims and drawings.